In machine tools such as lathes and machining centers, since chips are generated during processing, a discharge conveyor for discharging the chips from the processing section to outside of the machine tool is provided. With a discharge conveyor, a storage tank provided with an inlet for receiving chips and cutting fluid is provided below the processing section. Inside the conveyor, chips are conveyed rearwards and are collected by falling into a collection box from a discharge pipe that extends diagonally up. There are various types of such a discharge conveyor, including a drum type conveyor and a chip conveyor that uses an endless hinge belt. Among these, screw conveyors are desirable due their small dimension in the height direction. A conventional screw conveyor is disclosed in patent literature 1 below.
This screw conveyor has a screw rotatably assembled inside a tubular storage tank that includes an inlet on a top section, and an opening covered by perforated metal is formed on a top side of the storage tank for collecting cutting fluid. In the machine tool, chips generated during processing fall into the conveyor from the inlet open in the top direction, and are collected in the storage tank together with the cutting fluid. The chips are conveyed to the rear by rotation of the screw, are pushed along the discharge pipe, and are discharged to the outside to be collected. On the other hand, for the cutting fluid that has collected in the storage tank, the level of the fluid gradually rises until the fluid is discharged from the opening to the tank of the conveyor main body, and is then sent to a coolant device by a pump, such that a portion or all of the fluid can be reused or discarded.